PSN RES SCA LPMA

Saclay, France

PSN RES SCA LPMA

Saclay, France
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Peillon S.,PSN RES SCA LPMA | Fauvel S.,PSN RES SCA LPMA | Chagnot C.,CEA Saclay Nuclear Research Center | Gensdarmes F.,PSN RES SCA LPMA
Aerosol and Air Quality Research | Year: 2017

The goal of this article is to provide results on aerosol particles emissions of a laser Nd:YAG cutting technique used for the decommissioning of nuclear facilities. In particular, the study aims at characterizing the aerosol emitted during the cutting of steel specimens of different thicknesses and to study particulate emissions for cuts in air and under water. To do so, we calculate the emitted aerosol mass per unit area of cut. Overall, it was found that the mass of aerosol per unit area of cut by laser cutting decreases when the laser power and cutting speed increase. We also examine the performance of the height of the water column above the cut on the particle collection efficiency. We found that the driving phenomenon for particle collection is the scrubbing of particles by bubbles present in the water column. When cuts are realized under water, the production of aerosol particles mass per unit area of cut is reduced by a factor of 10 and limited below 70 g m–2. © Taiwan Association for Aerosol Research.


Peillon S.,PSN RES SCA LPMA | Roynette A.,PSN RES SCA LPMA | Grisolia C.,French Atomic Energy Commission | Gensdarmes F.,PSN RES SCA LPMA
Fusion Engineering and Design | Year: 2014

This work presents the results of experiments conducted with carbon microparticles collected in the tokamak Tore Supra in order to characterize their resuspension behaviour from a stainless-steel substrate when exposed to turbulent airflow. Experiments were conducted in a wind tunnel with controlled velocity profiles and monitored environmental conditions. A consequent amount of dust has been collected in the vessel of the tokamak and a bimodal particle size distribution of samples is first demonstrated. Comparison with resuspension of alumina powders with equivalent particle size distributions under turbulent airflow is also discussed. Results for both carbon and alumina microparticles are then compared to a theoretical resuspension model. Data reveal that exposing multilayer deposits with bimodal particle size distributions to low-speed flows (i.e. 3-10 m/s) induces a significant reduction of the mobilized fractions compared to what was predicted by the model. In addition, results helped to highlight some limitations in the model to physically describe changes in the adhesive strength that can occur with a polydisperse deposit. © 2014 Published by Elsevier B.V.


Bau S.,Institute National Of Recherche Et Of Securite | Witschger O.,Institute National Of Recherche Et Of Securite | Gensdarmes F.,PSN RES SCA LPMA | Thomas D.,University of Lorraine
Journal of Nanoparticle Research | Year: 2013

Due to the increasing use of nanomaterials in research and product development, it is probable that the number of situations of occupational exposure to them is also rising. The same is true for the number of workers. Although current research in nanotoxicology is far from conclusive, it is clear that relying on mass concentration and chemical composition alone is not appropriate in all cases and alternative measurement methods and approaches need to be developed. In this work, we propose a method based on simultaneous size-integrated measurements of two particle concentrations (number and lung-deposited surface area, CNC/NSAM), and on the estimation of the average size of potentially inhaled particles from the combination of these measurements. The proposed method could be part of a measurement strategy that is practical as it would use field-portable, commercially available aerosol instruments. In the absence of instruments providing real-time size-resolved measurements, this original approach can be carried out as considering that the ratio of these concentrations is a monotonous function of particle size. Indeed, the latter function depends only on the geometric standard deviation of airborne particle number size distribution, assumed to be lognormal. Compared to SMPS data for polydisperse aerosols having three chemical natures with count median diameters ranging from 64 to 177 nm, experimental results were obtained with acceptable relative discrepancies of ±30%. Though the method proposed is less accurate than traditional instruments like SMPS, it can be used for workplace air monitoring or as a screening tool to detect the presence of airborne nanoparticles. © Springer Science+Business Media 2013.


Yon J.,INSA Rouen | Liu F.,Carbon Black | Bescond A.,INSA Rouen | Caumont-Prim C.,INSA Rouen | And 3 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2014

The in situ optical characterization of smokes composed of soot particles relies on light extinction, angular static light scattering (SLS), or laser induced incandescence (LII). These measurements are usually interpreted by using the Rayleigh-Debye-Gans theory for Fractal Aggregates (RDG-FA). RDG-FA is simple to use but it completely neglects the impact of multiple scattering (MS) within soot aggregates. In this paper, based on a scaling approach that takes into account MS effects, an extended form of the RDG-FA theory is proposed in order to take into account these effects. The parameters of this extended theory and their dependency on the number of primary sphere inside the aggregate (1 < N p < 1006) and on the wavelength (266 nm < λ < 1064 nm) are evaluated thanks to rigorous calculations based on discrete dipole approximation (DDA) and generalized multi-sphere Mie-solution (GMM) calculations. This study shows that size determination by SLS is not distorted by MS effect. On the contrary, it is shown that fractal dimension can be misinterpreted by light scattering experiments, especially at short wavelengths. MS effects should be taken into account for the interpretation of absorption measurements that are involved in LII or extinction measurements. © 2013 Elsevier Ltd.


Gensdarmes F.,PSN RES SCA LPMA | Grisolia C.,French Atomic Energy Commission | Roynette A.,PSN RES SCA LPMA | Peillon S.,PSN RES SCA LPMA | And 3 more authors.
Fusion Engineering and Design | Year: 2013

Understanding the mobilization of dust in tokamaks is essential for proper machine operation and occupational worker exposure during maintenance operations. It is also a key issue for the safety assessment of ITER in Loss of Vacuum Accident (LOVA) scenario. Dust mobilization by airflow is strongly dependent on particle size and shape, and these characteristics are related to the specific process of erosion of the plasma facing components. Accordingly, it is important to develop techniques for in situ analysis of wall dustiness and potential dust mobilization by airflow. We propose a device, called DUSTER BOX, allowing to study dustiness of Tore Supra surfaces and to collect dust sample without mechanical stresses. This device consists in a simple airflow channel box and allows injecting a filtered airflow tangentially to the surface. The flow velocity parallel to the plasma facing components is 10 m/s and the friction velocity is 0.7 m/s which is the value needed to tear off particles greater than few microns from surfaces. After being resuspended, carbon dusts are collected on a membrane filter for weight analysis, size distribution analysis and electron microscope imaging. DUSTER BOX has been successfully used to realize a mapping of particles deposit in Tore Supra and to collect samples for size distribution analysis. © 2013 Elsevier B.V.


Ouf F.-X.,PSN RES SCA LPMA | Mocho V.-M.,PSN RES SCA LPMA | Pontreau S.,PSN RES SCA LPMA | Wang Z.,PSN RES SCA LPMA | And 2 more authors.
Aerosol Science and Technology | Year: 2014

The Institute of Radioprotection and Nuclear Safety (IRSN in French) is conducting research on the impact of a fire on the behaviour of containment devices such as high efficiency particulate air (HEPA) pleated filters for radioactive materials. This work aims to study the clogging of HEPA filters in case of fire involving realistic materials (polymers making up gloves boxes, waste treatment solvent, hydraulic oil, solid material mixtures making up a trash bin, electrical cables, and cabinets) used in nuclear facilities, from the medium to large scale. The clogging kinetics of industrial pleated HEPA filters is monitored by measuring the pressure drop of the filters and the filtered air temperature at a given filtration velocity (from 0.23 to 2.1 cm/s). Upstream HEPA filters, combustion aerosols are characterized in terms of size distribution, mass concentration, composition, and particle morphology using, respectively, a DMS500 (CambustionLTD), glass fiber filter sampling, and transmission electron microscope analysis of particles deposited on TEM grids. Particles emitted denote well-known fractal morphology, are composed of carbonaceous primary particles with diameters ranging from 31 nm to 48 nm and showing an high clogging efficiency. An empirical relationship has been successfully applied to the obtained results for a larger range of fuels, filtration velocities and fire conditions. Finally, experiments have been performed on a large-scale facility, using full-scale fire scenarios (electrical cabinet, constant, and variable filtration velocity) and a reasonable agreement was observed with our empirical relationship. At this scale, particles appear to be compact, with a complex composition and diameters close to 220 nm with a lower clogging efficiency. Copyright © American Association for Aerosol Research.


Thomas D.,CNRS Reactions and Process Engineering Laboratory | Ouf F.X.,PSN RES SCA LPMA | Gensdarmes F.,PSN RES SCA LPMA | Bourrous S.,CNRS Reactions and Process Engineering Laboratory | And 2 more authors.
Separation and Purification Technology | Year: 2014

This study presents a new pressure drop model developed for cakes composed of nanostructured particles. The cake structure is understood as a tangle of chains composed by juxtaposed primary particles with (aggregates) or without (agglomerates) a partial overlap. Since cake porosity is one of the main parameters determining aeraulic resistance, an experiment protocol based on the changes in deposit thickness as a function of the cake mass per surface area has been developed to accurately determine this parameter. To this end, the pressure drop and the porosity of the cakes created by the filtration of carbon nanoparticles aggregates and agglomerates on PTFE membrane were measured. The aggregate and agglomerate count median mobility diameters range from 91 nm to 170 nm and from 48 nm to 62 nm, respectively. The associated Peclet numbers range from 0.19 to 53 for filtration velocities of 0.01, 0.05 and 0.09 m/s. Initial experimental results indicate that the porosity of the cakes ranges from 0.94 to 0.984 in correlation with the Peclet number of the aggregates or agglomerates. The agreement between experimental results and the pressure drop model is fairly good. Of the experimental values, 95% are within plus or minus 25% of the theoretical value. © 2014 Elsevier B.V. All rights reserved.


Ouf F.-X.,PSN RES SCA LPMA | Mocho V.-M.,PSN RES SCA LPMA | Pontreau S.,PSN RES SCA LPMA | Wang Z.,PSN RES SCA LPMA | And 2 more authors.
Journal of Hazardous Materials | Year: 2015

For industrial concerns, and more especially for nuclear applications, the characterization of soot is essential for predicting the behaviour of containment barriers in fire conditions. This study deals with the characterization (emission factor, composition, size, morphology, microstructure) of particles produced during thermal degradation of materials found in nuclear facilities (electrical cables, polymers, oil and solvents). Small-scale experiments have been conducted for oxygen concentrations [O2] ranging from 15% to 21% in order to imitate the oxygen depletion encountered during a confined fire. Particles denote distinct shapes, from aggregates composed of monomers with diameters ranging from 31.2nm to 52.8nm, to compact nanoparticles with diameters ranging from 15nm to 400nm, and their composition strongly depends on fuel type. Despite the organic to total carbon ratio (OC/TC), their properties are poorly influenced by the decrease in [O2]. Finally, two empirical correlations are proposed for predicting the OC/TC ratio and the monomer diameter, respectively, as a function of the fuel's carbon to hydrogen ratio and the emission factor. © 2014 Elsevier B.V.


PubMed | PSN RES SCA LPMA, Aix - Marseille University and INSA Rouen
Type: | Journal: Journal of hazardous materials | Year: 2014

For industrial concerns, and more especially for nuclear applications, the characterization of soot is essential for predicting the behaviour of containment barriers in fire conditions. This study deals with the characterization (emission factor, composition, size, morphology, microstructure) of particles produced during thermal degradation of materials found in nuclear facilities (electrical cables, polymers, oil and solvents). Small-scale experiments have been conducted for oxygen concentrations [O2] ranging from 15% to 21% in order to imitate the oxygen depletion encountered during a confined fire. Particles denote distinct shapes, from aggregates composed of monomers with diameters ranging from 31.2 nm to 52.8 nm, to compact nanoparticles with diameters ranging from 15 nm to 400 nm, and their composition strongly depends on fuel type. Despite the organic to total carbon ratio (OC/TC), their properties are poorly influenced by the decrease in [O2]. Finally, two empirical correlations are proposed for predicting the OC/TC ratio and the monomer diameter, respectively, as a function of the fuels carbon to hydrogen ratio and the emission factor.

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